1. Field of Invention
This invention relates to improvements in the cooling of wheel assemblies and more specifically the cooling of the braking structures of the wheels of automotive vehicles.
Rolling wheels on moving vehicles, and particularly heavy vehicles such as trucks, trailers, and buses, especially in city transit opertion and on long hauls, generate considerable and sometimes excessive heat. This heat develops from friction in the application of the brakes, friction in the bearings, and the continual flexing of the ground-engaging portions of the tires. Furthermore, this mechanically developed heat is supplemented by the radiation from the sun and the hot pavement on hot days, the weight of the load being hauled, traveling speeds, and the sometimes continuous application of the brakes while descending steep grades, particularly in mountainous areas. As a result, tires on some trucks, trailers, and buses, especially in city transit operation and on long hauls, are wearing prematurely and failing before reaching the expected life of the tire. Failure of brakes due to overheating is also known to be a particular problem.
2. Description of Prior Art
Heat generated from wheel assemblies and brake structures on automotive vehicles, especially trucks, trailers, buses, and other heavy duty type vehicles is a well known problem.
Heretofore a wide variety of wheel assembly cooling means have been proposed and implemented for the resolution of the above mentioned heat problems. Some of these have merely provided air openings through wheel disk and/or hub caps. Others have involved baffled surfaces to promote air flow through such air openings, usually as a part of a hub cap structure, and thus are not well adapted for heavy duty applications because the design of heavy duty wheels in common manufacture provide no standard means for hub cap attachment.
One such invention incorporated the use of a fan like structure
(U.S. Pat. No. 3,168,348 Patented Feb. 2, 1965) mounted on the wheel co-axially of the hub for rotation therewith. The fan preferably comprised any desired number of blades, and was located within the outboard rim to increase the efficiency of the fan by directing all of the air flow axially of the fan.
Another cooling invention related to improvements in wheel structures by exposing a substantial central portion of the brake drum for heat dissipation at the outer side of the wheel (U.S. Pat. No. 3,051,276 Patented Aug. 28, 1962). In order to enhance heat dissipating and transfer value of the brake drum, the wheel body was specifically constructed for air circulation therethrough and in cooling relation to the brake drum therebehind.
Yet another cooling invention (U.S. Pat. No. 4,135,764 Patented Jan. 23, 1979) embodied air impelling vanes which were mounted in between the innermost and outermost wheels comprising a dual wheel construction. Upon rotation, the air vanes impelled air in the direction towards the hub.
Unlike the above mentioned patents, our invention differs in that each individual air inducing scoop attaches independently of one another to air holes on the outboard side of the wheel disk of the innermost wheel in a dual wheel assembly. The air inducing scoops then extend to fill the space between the innermost and outermost wheels to collect air upon rotation, and then direct that air as a powerful burst through the air holes of the wheel disk of the innermost wheel and over the braking structure to dissipate heat. On a single wheel construction, the air inducing scoops attach independently of one another to air holes of the wheel disk on the outboard side of the single wheel. Upon rotation, the air inducing scoops direct a powerful burst of air through the air holes of the wheel disk and over the braking structure to dissipate heat.
One invention (U.S. Pat. No. 2,754,939 Patented July 17, 1956) incorporates a strategy of cooling vehicle wheels that is somewhat similar in objectives, however is different in description and operation than our invention. The patent (U.S. Pat. No. 2,754,939) involved the use of air scoops attached to a wheel to impel a strong current of air through the wheel to ventilate a brake drum associated with the wheel. The air scoops are arranged in pairs with a pair for each air hole and each pair comprises an inboard scoop and an outboard scoop. In operation, increased air flow over the brake drum is generated as air scoops fastened to air holes on the outside of the wheel disk pick up air and create pressure, while air scoops fastened to air holes on the inside of the wheel disk create a vacuum.
Our invention differs from U.S. Pat. No. 2,754,939 in several respects. For one, our invention utilizes one-piece air inducing scoops that attach to air holes on the outboard side of a wheel disk to form a cup over the entire air hole in order to maximize the amount of air flow that can be impelled through the air hole. The prior art form (U.S. Pat. No. 2,754,939) is illustrated as being constructed out of two separate cups or louvers; an outboard scoop covering approximately 50% of the air hole, and an inboard scoop covering the remaining 50%, but in an inverted position with respect to the location of the outboard scoop. In addition, the openings of the inboard and outboard scoops face in opposite directions. The intention of this "dual scoop per air hole " design is to create an effective flow of air while the wheel is rotating by reason of the louvers at one side of the wheel disk picking air and creating a pressure and the louvers at the other side creating a vacuum. We have found by testing our invention, that in most cases, the wheel assemblies of vehicles that can benefit from our invention do not have sufficient area between the braking structure and wheel on the inboard side of the wheel to allow an inboard scoop or louver to be attached. This technicality prompted us to design our invention as a single air inducing scoop mounted on the outboard side of the wheel disk. And because our invention utilizes a single air inducing scoop per air hole, it is not an object of our invention to create a vacuum, by means of an inboard mounted scoop, to aid in cooling wheel assemblies.
The prior patents we have found do not appear to be well adapted, if at all, for effective action to circulate air through the air holes standard to wheel disks of existing manufacture for heavy duty vehicles of both single and dual wheel assemblies.
Furthermore, the cost of our invention will be less than the above mentioned prior art forms because our invention will be constructed out of heat-resistant durable plastic, readily adaptable to low cost plastic forming procedures as opposed to the often expensive metal fabricating processes required to fabricate the prior art forms we discovered. Moreover, because the air inducing scoops are constructed out of heat-resistant durable plastic, they will also be light in weight and less likely to adversely affect the balance of the wheels.
In addition, unlike some prior art forms, our invention has been designed for easy installation. The air inducing scoops can be readily attached on the outboard side of the wheel to air holes of the innermost wheel disk in a dual wheel assembly by means of several built-in sturdy plastic clips, and additional metal fasteners to provide extra stability. Likewise, the air inducing scoops can be readily attached in the same manner on the outboard side of the wheel to air holes of the wheel disk in a single wheel construction.